Technical Design DocumentsTechnical Design
Documents
The technical and operational specifications of the Once-Only Technical System, laid down in the Commission’s Implementing Regulation ((EU) 2022/1463) setting out the system, are complemented by detailed, non-binding technical design documents jointly prepared by the Commission and Member States.
Main chapters
This is the v1.0.5 release of the Technical Design Documents from June 2024.
Chapter 1
Introduction - High Level
Architecture
This chapter introduces the high-level architecture of the Once-Only Technical System and the key concepts and themes found in the subsequent chapters.
Chapter 2
User Identification, Authentication and Record Matching
This chapter explains how those submitting or receiving evidences through the Once-Only Technical System are identified and authenticated.
Chapter 3
Common Services
This chapter looks at the Common Services necessary for the proper execution of the evidence exchange process. You can also learn more about APIs supporting these common services.
Chapter 4
Evidence Exchange
This chapter introduces evidence exchange in the Once-Only Technical System, which is based on bilateral data exchange between relevant authorities.
Chapter 5
Data Models
This chapter looks at the data models that streamline the exchange of evidences, together with a methodology for defining new data models and code lists.
Chapter 6
OOTS Guidance & UX
Recommendations
This chapter provides an overview of how the Once-Only Technical System works as part of the wider Single Digital Gateway and looks at the first set of UX recommendations.